Printing ink dispersions comprising discrete carbon nanotubes

Abstract

This present invention relates to oxidized, discrete carbon nanotubes in dispersions, especially for use in printing inks. The dispersions can include materials such as elastomers, thermosets and thermoplastics or aqueous dispersions of open-ended carbon nanotubes with additives. A further feature of this invention relates to the development of a dispersion of oxidized, discrete carbon nanotubes that are electrically conductive.

The invention claimed is: 
     
       1. A dispersion suitable for coatings or printing inks wherein the dispersion comprises a plurality of oxidized, discrete carbon nanotubes and at least one polymeric dispersing agent, wherein the oxidized, discrete carbon nanotubes have an aspect ratio of 25 to 500, are multiwall, and are present in the range of greater than zero and up to about 30% by weight based on the total weight of the dispersion, and wherein the aspect ratio of the discrete carbon nanotubes is bimodal. 
     
     
       2. The dispersion of  claim 1  wherein at least 70 percent by weight of the nanotubes in the dispersion are discrete based on the total weight of nanotubes in the dispersion. 
     
     
       3. The dispersion of  claim 1  wherein at least a portion of the oxidized, discrete carbon nanotubes comprise an oxidation species selected from carboxylic acid or a derivative carbonyl containing species wherein the derivative carbonyl species is selected from ketones, quaternary amines, amides, esters, acyl halogens, and metal salts. 
     
     
       4. The dispersion of  claim 1  wherein the oxidized, discrete carbon nanotubes comprise an oxidation species selected from hydroxyl or derived from hydroxyl containing species. 
     
     
       5. The dispersion of  claim 1  wherein the dispersion further comprises a bonded or unbonded a component selected from the group consisting of proteins, antibodies, deoxyribonucleic acids, ribonucleic acids, metal salts, metal oxides, and combinations thereof. 
     
     
       6. The dispersion of  claim 1  wherein the polymeric dispersing agent comprises one or more components selected from the group consisting of water-soluble homopolymers, water-soluble random copolymers, water-soluble block copolymers, water-soluble graft polymers, cellulose derivatives, amino acid polymers, polyacrylates, polyethylene sulfonates, polystyrene sulfonates, polymethacrylates, polysulfonic acids, condensation products of aromatic sulfonic acids with formaldehyde, naphthalene sulfonates, lignin sulfonates, copolymers of acrylic monomers, polyethyleneimines, polyvinylamines, polyallylamines, poly(2-vinylpyridines), block copolyethers, block copolyethers with polystyrene blocks, polydiallyldimethylammonium chloride, polyvinylidene fluorides, fluorine containing polymers, polysaccharides, and mixtures or copolymers thereof. 
     
     
       7. The dispersion of  claim 1  wherein the polymeric dispersing agent comprises one or more components selected from the group consisting of polyvinyl alcohols, copolymers of polyvinyl alcohols and polyvinyl acetates, polyvinyl pyrrolidones, carboxymethyl cellulose, carboxypropyl cellulose, carboxymethyl propyl cellulose, hydroxyethyl cellulose, starch, gelatin, gelatin derivatives, polylysine, polyaspartic acid, and mixtures thereof. 
     
     
       8. The dispersion of  claim 1  wherein the polymeric dispersing agent comprises from about 0.01 wt. % to about 10 wt. % based on the weight of the dispersion. 
     
     
       9. The dispersion of  claim 1  which further comprises a surfactant comprising a sulfate moiety. 
     
     
       10. The dispersion of  claim 1  which further comprises a surfactant comprising a phosphate. 
     
     
       11. The dispersion of  claim 1  which further comprises a surfactant comprising a quaternary amine. 
     
     
       12. The dispersion of  claim 1  which further comprises a surfactant comprising an ethylene oxide moiety. 
     
     
       13. The dispersion of  claim 1  which further comprises a sulfonated polymer selected from the group consisting of ligno-sulfonate, sulfonated polystyrene, and combinations thereof. 
     
     
       14. The dispersion of  claim 1  which further comprises an organic solvent. 
     
     
       15. The dispersion of  claim 14  wherein the organic solvent comprises one or more compounds selected from the group consisting of alcohols, ethers, ketones, dioxalane, acetates, glycols, and mixtures thereof. 
     
     
       16. The dispersion of  claim 1  wherein the dispersion has a dynamic viscosity of less than about 0.5 Pa·s. 
     
     
       17. The dispersion of  claim 1  further comprising water. 
     
     
       18. The dispersion of  claim 1  further comprising an inorganic oil or solvent. 
     
     
       19. The dispersion of  claim 18  wherein the inorganic oil or solvent comprises a polysiloxane. 
     
     
       20. The dispersion of  claim 1  wherein the dispersion is suitable for use as an electrically conductive coating. 
     
     
       21. The dispersion of  claim 1  wherein the dispersion at least partially coats a surface of an article. 
     
     
       22. The dispersion of  claim 1  wherein the dispersion is suitable for use as an ink formulation additive in less than 35 micron resolution electro-conducting printing inks. 
     
     
       23. The dispersion of  claim 1  wherein the dispersion is heat curable, photocurable, or UV curable. 
     
     
       24. The dispersion of  claim 1  further comprising at least one thermoplastic polymer. 
     
     
       25. The dispersion of  claim 1  further comprising at least one resin. 
     
     
       26. The dispersion of  claim 1  further comprising at least one partially electrically conductive additive. 
     
     
       27. The dispersion of  claim 26  wherein the at least one partially electrically conductive additive is selected from the group consisting of lead, lead derivatives, carbon black, graphite, graphene, graphene oxides, paramagnetic particles, metallic particles, sub-micron graphite, carbon fibers, graphite fibers, and mixtures thereof. 
     
     
       28. The dispersion of  claim 1  further comprising an additive and wherein said dispersion is reflective or absorptive of one or more electromagnetic fields. 
     
     
       29. The dispersion of  claim 28  wherein the reflectiveness, absorptiveness, or both may be controllably adjusted by changing the concentration of the oxidized, discrete carbon nanotubes in the dispersion. 
     
     
       30. The dispersion of  claim 28  wherein the reflectiveness, absorptiveness, or both may be controllably adjusted by changing a voltage applied to the dispersion. 
     
     
       31. The dispersion of  claim 1  further comprising siloxane and an additive selected from the group consisting of aluminum oxide and boron nitride.